A stock trope of literature is the king who believes that his kingdom will last forever, only to see it collapse under his own hubris (Exhibit A is Percy Bysshe Shelly's Ozymandias). But the trope is based on historical fact. Many great civilizations vanished without a trace, and why their disappearance still haunts us today.

This episode is the first in a three-part series that will look atf the greatest lost civilizations in history. Some were millenia ahead their neighbors, such as the Indus Valley Civilization, which had better city planning in 3,000 B.C. than any European capital in the 18th century. Others were completely myth-based, such as Plato's lost city of Atlantis, a technological advanced utopia that sank into the ocean "in a single day and night of misfortune"

Whatever the nature of their disappearance, these lost civilizations offer many lessons for us today -- even the greatest of societies can disappear, and that includes us.